PPRuNe Forums - View Single Post - Maintenance Lapse Identified as Initial Problem Leading to Lion Air Crash
Old 2nd Apr 2019, 20:36
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Double07
 
Join Date: Apr 2014
Location: Minneapolis, MN
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Originally Posted by wiedehopf
The sensor that was removed could have been defective in a way that doesn't produce a wrong AoA.
Actually the maintenance log indicates that before the AoA sensor replacement there was no "Airspeed disagree" or anything else that would indicate an "AoA disagree" but rather air data missing intermittently for the captain.

So to me it seems very likely that during that replacement the offset error/ AoA disagree was introduced.
But it's not at all clear if the new sensor was the problem or the act of replacing it introduced an cabling or other error down th eline.
My two posts above explained how a large offset angle could be induced in the AoA sensor during the testing process after sensor replacement. This would have been made more likely by a failure during a rework process to tighten a set screw to a required torque in an internal gear of the AoA sensor. This led me to postulate that the replacement sensor may have been a reworked sensor, which was subsequently confirmed by an actual report. This is all consistent with the latest report that the sensor failed a test at the manufacturer in Minneapolis. This does not mean that the original sensor as manufactured by Rosemount was defective. It merely means that a shoddy rework process in a repair facility may have left the sensor susceptible to change during the installation testing process. One of my original posts above describes how this may have happened.
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